Used Exmark Metro Frame Cracks Help?

Hey guys I just picked up a 96-97 Exmark Metro recently. I have been keeping my eyes out for a walk behind for my house for a while and
was waiting until I found a good deal. Well I thought I got a good deal Mower ran great when I checked it out and had lots of Power. The deck had a few rust spots and a small crack that could be easily welded i thought no big deal
I should have given it a better inspection because after getting it home and cleaning it up the grime I found two hidden cracks in the frame right above where the deck attaches. on both sides. One side is not all the way through . I attached some pics of the bad side

What do you guys think is this something that can be easily welded? will the engine need to be removed to fix it. I probably overpaid. I am pretty sure the guy I bought it off of had no clue they where there but I spent that last few weeks looking old bob-cats etc that where in worse condition for the same price. I guess I go a little two excited and should have clean off more of the grime . Besides those the mower runs and cuts great. What do you guys think I should do